Anyone ever experienced this before?
Here's the scoop.
Vortec heads modified for screw in studs, guide plates and 1.6 rockers.
Comp guide plates, Pro Magnum 1.6 roller rockers and pushrods.
GM studs.
Thousands of miles of trouble free performance before this.
The stud broke off just below the poly lock. RPM at the time was about 2000 while cruising on the interstate on my way to Virginia.
In all my years of hot roddong, I've never had this happen before.

 

Sounds fairly bizarre. Your cam isn't that radical. Probably just a bad forging. Replace it and go on.

 

My thinking as well.
During one of the last rebuilds I found one of the studs to have slightly pulled threads and it made installing the poly lock somewhat difficult. I replaced it with another stud from a local racer/rebuilder. Once I have them all replaced with the new ARP stuff I bought for the single stud roadside repair, I'll check to see if the previously replaced stud is the one that failed. I may have installed a well used part that had fatigued.
The tow truck driver that picked me up at the side of a New York state hiway had a spare in his toolbox! That got me to Virginia where a local speed shjop had a full set of ARP studs hanging on the wall.
God bless the Gen 1 small block Chevy. Parts are available everywhere.

 

Amen to that!

 

For what it's worth, the original screw in studs (manufacturer unknown) put the allen screw about 2 threads (.080") below the top of adjusting nut. The ARP 7101 studs (which I bought for the on the road repair) are 1.750" long which ended up being about 1/10" shorter than the originals. That put the lock screw more than 4 threads below the adjuster and reduced the thread engagement in the nut by that amount. Thinking was that I would pushing my luck with the new studs so I opted for the ARP 7104 which are 1.875" long. After adjustment, the lock screw is flush with the nut and there's more thread engagement than before.
With the longer and stronger ARP hardware I should be good to go.

 

I know this a really old thread but I just had this happen to me the stud broke off (cylinder 5 exhaust), the pushrod bent at a good 45* angle the rocker arm just sort of sat back with taking no damage what so ever and the intake pushrod on the same cylinder slipped out and just laid in the lifter valley and the rocker arm was sill attached to that stud fine and dandy!!! Pulled everything apart just to be sure and everything else is just fine no other damage all I needed to do was replace the stud and 1 pushrod. Talk about dodging a bullet